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Jun 30, 2018
06/18

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V. Sauli

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We present the solution of Schwinger-Dyson and Bethe-Salpeter equation (BSE) for a light flawour non-singlet spinless meson in Minkowski space. The equations are solved in momentum space without the use of the auxiliary Euclidean space. To exhibit that Minkowski space non perturbative calculations are actually possible is the main purpose of presented paper. According to confinement, the quark propagator is regular in momentum space, which allows us to look for the BSE solution directly in the...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice

Source: http://arxiv.org/abs/1411.2568

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Sep 20, 2013
09/13

by
V. Sauli

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A new method of solution of the Bethe-Salpeter equation for a pseudoscalar quark-antiquark bound state is proposed. With the help of an integral representation, the results are directly obtained in Minkowski space. Dressing of Green's functions is naturally taken into account, thus providing the possible inclusion of a running coupling constant as well as quark propagators. First numerical results are presented for a simplified ladder approximation.

Source: http://arxiv.org/abs/0802.2955v1

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Sep 18, 2013
09/13

by
V. Sauli

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Using the method of Fukuda and Kugo \cite{FUKKUG} the continuation of Euclidean solution is performed to the timelike axis of fourmomenta. It is shown that assumed presence of the real simple pole in quark propagator is not in agreement with the solution. The simple pole disappears because of the discontinuity in the resulting quark mass function.

Source: http://arxiv.org/abs/0704.2566v3

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Sep 18, 2013
09/13

by
V. Sauli

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The loop structure of two point Green's functions is investigated in the Wess-Zumino model in the formalism where the auxiliary fields are integrated out. In the usual frame of perturbation theory the deviation from the non-renormalization theorem is explicitly shown. It is shown that Ward identity are not satisfied in this approach. Further we go beyond perturbation theory by solving a system of regularized Schwinger-Dyson equations (SDEs). The mass splitting between fermions and bosons, which...

Source: http://arxiv.org/abs/hep-th/0502094v1

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Jun 27, 2018
06/18

by
V. Sauli

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Mechanism for generation of vector meson resonances is studied in the framework of QCD Dyson-Schwinger equations, which are defined and actually solved in Minkowski space. It is suggested that the timelike pion form factor is generated by the interference of the background quark loops together with the resonant structure predominantly created in the photon-quark-antiquark vertex. It is suggested that QCD Green's functions involving quark fields are oscillating for timelike arguments, which...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1505.03778

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Jun 30, 2018
06/18

by
V. Sauli

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Propagators approximated by a meromorphic functions with complex conjugated poles are widely used to model infrared behavior of QCD Green's functions. In this paper, analytical solutions for two point correlator made out of functions with complex conjugated poles or branch points have been obtained in the Minkowski space for the first time. As a special case the Gribov propagator has been considered as well. The result is different from the naive analytical continuation of the correlator...

Topic: High Energy Physics - Theory

Source: http://arxiv.org/abs/1412.7863

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Sep 17, 2013
09/13

by
V. Sauli

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This is an abstract of authors PhD thesis which is devoted to studies of quantum field models with strong coupling. The {\em Schwinger-Dyson equations} (SDEs) in momentum representation are solved in Minkowski space. The original version of the paper hep-ph/0108160 is included in. The full text of author's PhD thesis can be found at this WWW: 'http://gemma.ujf.cas.cz/~sauli/papers.html'

Source: http://arxiv.org/abs/hep-ph/0108160v5

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Sep 18, 2013
09/13

by
V. Sauli

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Using the formalism of Bethe-Salpeter equation (BSE) the Higgsonium bound state is studied. The condition for formation of Higgsonium bound states are discussed in SM and in the simple extension of.

Source: http://arxiv.org/abs/0806.3454v1

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Sep 21, 2013
09/13

by
V. Sauli

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The propagator of confined quarks is calculated for timelike momenta by transforming Minkowski Greens functions to the Temporal Euclidean space. Based on the framework of the Schwinger-Dyson equations the QCD quark propagator is obtained in two approximations which differ by assuming behaviour of gluon propagator. In both studied cases we get universal result for the light quarks: The quark mass function becomes complex bellow expected perturbative threshold, the obtained absolute value of the...

Source: http://arxiv.org/abs/0902.1195v2

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Sep 20, 2013
09/13

by
V. Sauli

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The new method of solution of the Bethe-Salpeter equation for quark-antiquark pseudoscalar bound state is proposed. With the help of integral representation the results are directly obtained in Minkowski space. Dressing of Greens functions is naturally considered providing thus the correct inclusion of the running coupling constant and the quark propagators as well as. The first numerical results are presented for a simplified ladder approximation.

Source: http://arxiv.org/abs/hep-ph/0404189v2

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Sep 17, 2013
09/13

by
V. Sauli

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The running of the Top quark mass is considered in the nonperturbative framework of the Schwinger-Dyson equation. Based on the input of physical pole mass meassured at the Tevatron the method provides the resulting mass function which is almost constant at low spacelike and timelike scales. The skeleton loops including Standard Model Higgs and gluons are taken into account. The dominant two-loop skeleton contribution with triplet Higgs interaction is considered in addition to one loop dressed...

Source: http://arxiv.org/abs/0711.1899v3

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Sep 18, 2013
09/13

by
V. Sauli; Z. Batiz

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We present an elementary nonperturbative method to obtain Green's functions (GFs) for timelike momenta. We assume there are no singularities in the first and third quadrants of the complex plane of space momentum components and perform a 3d analogue of Wick rotation. This procedure defines Greens functions in a timelike Euclidean space. As an example we consider the quark propagator in QCD. While for weak coupling, this method is obviously equivalent to perturbation theory, for a realistic QCD...

Source: http://arxiv.org/abs/0806.2817v2

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Sep 21, 2013
09/13

by
V. Sauli; Z. Batiz

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Without any analytical assumption we solve the ladder QED2+1 in Minkowski space. Further, we transform Greens functions to the Temporal Euclidean space, wherein we show that in the special case of ladder QED2+1 the solution is fully equivalent to the Minkowski one. The obtained complex fermion propagator exhibits confinement because of the lack of the pole at the real timelike $q^2$ axis.

Source: http://arxiv.org/abs/0901.0110v3

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Sep 19, 2013
09/13

by
V. Sauli; F. Kleefeld

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Within the Pauli-Villars regularization technique the fermion propagator is studied in the framework of Schwinger-Dyson equations in the Euclidean space. Making the generalization of Fukuda and Kugo proposals, the analytical continuation is performed into the timelike region of fourmomenta. The massive gauge boson kernel is considered and the fermion propagator pole structure is discussed in detail.

Source: http://arxiv.org/abs/hep-ph/0701161v3

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Sep 18, 2013
09/13

by
V. Sauli; J. Adam

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The Schwinger-Dyson equation for a scalar propagator is solved in Minkowski space with the help of an integral spectral representation, both for spacelike and timelike momenta. The equation is re-written into a form suitable for numerical solution by iterations. This procedure is described for a simple unphysical Lagrangian with a cubic interaction, with future extensions to more realistic theories in mind.

Source: http://arxiv.org/abs/hep-ph/0110298v1

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Sep 23, 2013
09/13

by
V. Sauli; Z. Batiz

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Without any analytical assumption we solve the ladder QED2+1 in Minkowski space. Obtained complex fermion propagator exhibits confinement in the sense that it has no pole. Further, we transform Greens functions to the Temporal Euclidean space, wherein we show that in the special case of ladder QED2+1 the solution is fully equivalent to the Minkowski one. Obvious invalidity of Wick rotation is briefly discussed. The infrared value of the dynamical mass is compared with other known approaches,...

Source: http://arxiv.org/abs/1006.0612v1

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Sep 20, 2013
09/13

by
V. Sauli; J. Adam; P. Bicudo

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The fermion propagator is studied in the whole Minkowski space with the help of the Schwinger-Dyson equations. Various integral representations are employed to get solutions for the dynamical breaking of chiral symmetry in different regimes of the coupling constant. In particular, in the case of massive boson, we extend the singularity structure of the fermion propagator to the two real pole Ansatz.

Source: http://arxiv.org/abs/hep-ph/0607196v3